Cereal Sawdust
The sawdust-like material accumulating at the bottom of the cereal bag. It is often poured on top of the last bowl of cereal, by accident, as you always forget it is going to be there. Cereal sawdust is not pleasant.
I woke up this morning and poured some cereal. Not much left in the box, just a few flakes and then a ton of cereal sawdust. I was pissed.